Labyrinth sealing devices are commonly used to provide a dynamic seal between a rotating shaft and a bearing housing. The sealing device excludes contaminates from the bearing housing while also preventing loss of bearing lubricants. In some applications, the lubrication level of the housing is above the lowest point of the seal. Commonly, the lubrication will eventually work through the seal and leak, where a non-contact seal is used. A contact type seal is desirable in such applications.
In a typical rotor and stator configuration, it is important to keep the rotor and stator from contacting one another. The rotor spins at very high speeds. If a surface of the rotor contacts a surface of the stator at these speeds, frictional heat develops, the parts wear and the overall efficiency of the apparatus declines. It is, therefore, important to keep the rotor and stator separate. The seal between the rotor and stator keeps them separate in the radial direction by providing a low friction contact between the two. It would be beneficial if the same seal could also prevent contact in the axial direction.
A further problem occurs when the housing is “flooded” with lubricant. A flooded housing refers to a bearing cavity with an excess of lubricant, thus “flooded”. Traditional non-contacting seals do not function properly if used in a flooded housing.
Various seal devices have been previously developed to provide a dynamic seal between rotating shafts and a bearing housing. However, these previous designs have not resolved all of the operational issues experienced with these types of seals. For example, U.S. Pat. No. 6,234,489 to Orlowski et al. discloses a seal that includes a rotor and a stator. Enclosed within the rotor and stator is an insert that has an annular resilient member to hold one side of the insert in firm contact with an outer radial surface of the rotor. The shortcoming of this design is that, in its preferred configuration, the annular resilient member is provided as an o-ring.
Another seal design, disclosed within U.S. Pat. No. 6,386,546 to Fedorovich, includes a rotor and stator that are arranged to create a labyrinth portion and a contact portion. The stator includes one or more flanges biased toward the rotor surface to create the contact portion of the seal. The inherent problem with this type of seal is that the lay-down lip or flange biased toward the rotor cannot handle misalignment. Once the seal is misaligned, the lip gets flexed to one side of the seal and is then permanently deformed. Lubrication can then leak under the sealing lip if the misalignment is removed.